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Miller Bobcat Three Phase Motor Run Speed Issues

10-04-2012, 07:35 AM

I have a Bobcat Three Phase with a Kohler CH20s engine. I am having an issue where the motor is running way too fast. I have gone through the steps of adjusting the governor and adjusting the run speed as prescribed in the manual with no success. I can manual move the governor arm over and drop the rpms to acceptable levels but it does not move on its on. My thoughts are it may be the internal portion of the governor that is not operational.

However, in the run-idle position, the motors does not come down to idle position without manually moving the governor arm.

Its running at such a high speed it has melted the wire going to the large R2 resistor mounted on the upright.

Comment

Did you not adjust the adjuster arm left of the exhaust, with the 3/8" nut and lock nut. Or did you move the govenor spring which is definately a no, no...

I adjusted the nut and locknut. I did not move the govenor spring from the #3 hole in the arm. I actually adjusted the nut so loose there was no tension on the governor spring at all, with still no decrease in engine speed.

Comment

Thanks for the info. I'm a little confused on one part. I'm unsure if the shaft is threaded or not. My serial number is LE114xxx. Is there a range of serial numbers where the shaft is tapered and will pop off as you describe?
The below link suggests that from Serial No. LE294171 to present it is a threaded shaft.

The owners manual for my Serial number range appears to show a threaded shaft. Is there an easy way to identify the shaft type before I start. I don't want to be prying on the stator housing to hard trying to pop it off, if its a threaded shaft.

Comment

1) Remove brushes/brush holder.
2) Unbolt engine from frame and unhook harness, battery cables and fuel line.
3) Remove (4) bolts holding stator halves together.
4) Pull engine, rotor and front half of stator housing as a unit from back half of stator housing.
5) Seperate rotor from engine using proper wrench on flats of rotor shaft on bearing end. A sharp strike or two on the wrench with a good sized hammer should break the threads loose. Turns off the crankshaft in CCW direction. If stuborn and won't break free, you'll likely have to hold the engine flywheel while stiking the wrench.

Comment

1) Remove brushes/brush holder.
2) Unbolt engine from frame and unhook harness, battery cables and fuel line.
3) Remove (4) bolts holding stator halves together.
4) Pull engine, rotor and front half of stator housing as a unit from back half of stator housing.
5) Seperate rotor from engine using proper wrench on flats of rotor shaft on bearing end. A sharp strike or two on the wrench with a good sized hammer should break the threads loose. Turns off the crankshaft in CCW direction. If stuborn and won't break free, you'll likely have to hold the engine flywheel while stiking the wrench.

Worked on the Bobcat this weekend. These directions worked like a champ, had the motor on the bench in less than an hour. Turns on the governor was trashed. Replaced the governor and bolted everything back together and shes back to humming along...however now I've got another issue. It does not want to come down from run speed in the run/idle position. Is there an procedure for testing the idle solenoid?